Often it is necessary to provide markings on various web or sheet formed products. Preferably, the markings are applied to the web or sheet products as they are undergoing other processing. For example, roofing materials, such as asphalt shingles, commonly are produced in a process line in which a web of sheet material, made of organic or fiberglass material, is drawn from a supply roll through (1) a coating station in which the web is coated with a hot liquid tar or asphalt, (2) a surfacing station in which granular surfacing material is directed onto the hot liquid coating, (3) a cooling and press roll station in which the granular surface material is pressed into the hot liquid coating and sheet material and coating are cooled by spraying a cooling liquid onto the moving sheet material and (4) cutting and stacking stations in which the cooled sheet material is cut into predetermined-size shingles and stacked.
Roofing products include a variety of different shingles and rolls each of which is designed to be nailed down in a particular location. In order to help the roofers who install the products determine where a particular roofing product should be nailed, roofing material processing lines can include a nail marking system. A typical nail marking system uses one or more marking wheels to apply a rough line that runs the length of the roofing product identifying where the particular roofing product should be nailed. The marking wheels pick-up the marking fluid, which is a mixture of industrial latex paint and water, from a trough to which the marking fluid is pumped. Known water/paint mixtures used as marking fluids have water to paint mix ratios of 70/30 to 40/60.
Roofing material processing lines are now running at faster and faster speeds as compared to in the past with most roofing material lines running at close to 750 ft/min. Unfortunately, at higher speeds, the line produced by the marking wheel in conventional nail marking systems can include skips or become crooked, ragged and/or faint. Because improperly marked roofing products must be scrapped or rejected, failure of the marking system can be expensive and time consuming.
In addition, nail marking systems using applicator wheels are quite messy and relatively labor intensive and expensive to maintain. For example, because of paint build-up, the applicator wheels have to be cleaned and replaced on a regular basis. Moreover, the paint used in the marking fluid is relatively expensive. However, it is difficult to monitor and control paint utilization with wheel and trough marking systems leading to further inefficiencies.